Onchocerciasis control has long played a pioneering role in the field of public health. Since the 1950s, vector control with larvacides at blackfly breeding sights has been used to limit transmission. Initial efforts at the local level eventually proved insufficient to impact the disease due to its regional epidemiology. As a result the Onchocerciasis Control Program (OCP) was formed in 1974 in West Africa. Employing vector control on a regional scale, the OCP began to significantly reduce transmission of O. volvulus the region.
In the 1980s, Merk & Co. demonstrated that their drug Mectazin (ivermectin), formerlly used for treatment of other animal helminthes, was an effective microfilaricide for O. volvulus. Requiring only annual or biannual oral administration, ivermectin was the first microfilaricide with realistic potential as a mass treatment. In 1987, Merck pledged to make ivermectin available to all those who need it for as long as needed; with this pledge public health mass treatment programs became feasible.
The OCP integrated ivermectin distribution with vector control at some locations in West Africa, but continued with vector control activities. New programs formed in sub-Saharan Africa and the Americas to organize ivermectin distribution programs. The African Program for Onchocerciasis Control (APOC) was formed in 1995, expanding treatment distribution to 19 new countries. APOC’s principle strategy is establishment of sustainable Community Directed Treatment with Ivermectin (CDTI) programs. In 1996, many public and private partners collaborated to form the Onchocerciasis Elimination Program for the Americas (OEPA) to improve mass treatment efforts. The coalition provides financial, managerial, and technical support to distribution programs in 6 countries. (31, 32, 33, 34, 36, 39)
Acheivements
These onchocerciasis control programs have been noted as some of the most successful public health partnerships. They have prevented over a million cases of blindness, greatly reduced morbidity in endemic regions, and thus strengthened economic productivity. In West Africa alone, the OCP “added over one million years of productive labor to the economies of participating countries” (33). Research has played an important role throughout the development of these initiatives and made significant contributions to public health. The CDTI strategy pioneered community health worker programs that empower communities and create sustainable structures for health promotion. Rapid epidemiological assessment and modeling methods developed for onchocerciasis also have many potential applications for public health. In West Africa , the OCP was so successful in virtually stopping transmission and creating sustainable programs that it was official closed in 2002.
(33, 34, 35, 40, 42)
(45)Looking to the Future
International experts on onchocerciasis gathered at the Carter Center in Atlanta Georgia in 2002 to evaluate the ultimate eradicability of onchocerciasis. It was concluded that regional elimination is possible using current strategies in the Americas, Yemen and certain locations in Africa, but not complete eradication due to challenges in Africa. In Africa, Onchocerciasis is wide spread across extensive regions, while in the Americas the disease is found in limited foci. The Simulium vectors in Africa are remarkably efficient and vector control is becoming more difficult as human and fly migration is changing distribution. Migration also reintroduces the disease into controlled areas and prevents adequate population coverage. Current treatments and initiatives have greatly improved onchocerciasis control, but they have not proved sufficient to entirely halt transmission. Public health programs need new approaches and treatments to be developed before eradication can be achieved.
(14, 38, 39, 40, 42, 46)